This invention relates to a bearing for a timepiece gear train and, more particularly to a technique to improve the assembly of the gear train.
Conventionally, the assembly of a wheel and pinion mechanism and a bridge requires a great deal of skill and time since the wheel and pinion mechanism generally maintains the equilibrium in a given vertical orientation during assembly at its upper potion and can easily fall or tilt from the vertical because of unstability when the wheel and pinion mechanism is set in a base plate. As a countermeasure, members between the base plate and the bridge or a concave portion of the base plate are approximated to the wheel and pinion mechanism. However, in consideration of the play of the wheel and pinion mechanism, a relatively wide gap is required and if the gap is not large enough the wheel and pinion mechanism will contact the approximated members and disturb the rotation of the wheel and pinion mechanism. Moreover, the configuration of such members and of the concave portion of the base plate are complicated and result in a rise in the price of manufacture. Furthermore, as for small-sized women's watches, the above mentioned countermeasures cannot be taken because of lack of available space.
The present invention aims to simplify the train construction and assembly of the gear without a rise in the cost of manufacture by eliminating the above mentioned difficulty and insufficiency, the substance of which is to prevent falling or tilting of the wheel and pinion mechanism by means of a specially shaped bearing of the train.
Hereinafter the present invention will be illustrated in detail.